The stethoscope was invented in 1816 by a French doctor, Rene Laennec.

Before, doctors had placed their ear to the patient's chest to hear the sounds of the lungs and heart.

But to spare the blushes of a female patient, he rolled up sheets of paper and placed one end to his ear and the other to her chest.

Laennec discovered he could hear the sounds loudly and clearly.

He subsequently made models out of wood, known as monaural stethoscopes because they had only one earpiece.

Binaural stethoscopes with two earpieces, the version still used today, came into use in the 1860s.

"Stethoscope" derives from the Greek words for "breast" and "look at".

Over that time, it has changed little, apart from a change from one earpiece to two earpieces in the 1860s.

Small and smart

However, Prof Jagat Narula and associate professor Bret Nelson, from Mount Sinai School of Medicine in New York, believe that handheld ultrasound devices are set to take over from the traditional stethoscope.

They say this is because ultrasound technology is becoming more accurate, the devices are reducing in size and their cost gradually decreasing.

They write: "Several manufacturers offer hand-held ultrasound machines slightly larger than a deck of cards, with technology and screens modelled after modern smartphones."

They say these would allow doctors to diagnose illnesses quickly, particularly in emergencies, reduce complications and guide them when doing invasive procedures.

Using the ultrasound screen, doctors can see images of heart activity that could be sent ahead to a hospital A&E, they suggest.

Although point-of-care ultrasound is a new field and many clinicians have not been trained how to use it, the authors give examples of how the technology can be used fully in harsh environments, such as combat support hospitals, refugee camps and after disasters such as the Haitian earthquake in 2010.

They conclude: "Certainly the stage is set for disruption; as LPs were replaced by cassettes, then CDs and MP3s, so too might the stethoscope yield to ultrasound."

The stethoscope has long been the main tool in the doctor's toolkit

Listening skills

In the UK, cardiologists are adamant that the stethoscope will not be replaced.

Dr Sarah Clarke, a consultant cardiologist at Papworth Hospital in Cambridge and vice-president of the British Cardiovascular Society, says the stethoscope is a doctor's main diagnostic tool.

"We don't leave home without it. You can't replace what you hear if you're a doctor. It's a big part of our training.

"We are taught to listen to everything in a patient examination and put it all together, alongside what the patient is telling us.

"A picture isn't enough. You've got to put it into context. A handheld ultrasound doesn't give you the same level of diagnostic information or the same detail.

"The skill is in interpreting what you hear, in listening to the heart and the lungs which are key in diagnoses."

Dr Clarke says that a doctor may decide to do an ultrasound on a patient - using a large machine, not a handheld one - but only after listening to the heart and lungs using a stethoscope.

She adds: "The stethoscope is our first port of call, the main tool in our toolkit. That won't change."

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